Monoclonal antibodies (MoAb) selective for tumors have therapeutic potential.1,2 The introduction of hybridoma technology by Kohler and Milstein in 19753 and the advances in molecular biologic techniques have greatly expanded the potential of MoAb in human cancers. Anti-CEA antibody in colorectal cancer,4 anti-CD20 antibodies in lymphoma,5 anti-HER2 antibodies in breast cancer,6 anti-tenascin antibodies in glial brain tumors,7 MoAb M195 against CD33 in acute leukemia8 and anti-TAG-72 antibodies in colon cancer9 have shown efficacy in clinical trials. Our laboratory has developed the MoAb 3F8 which targets the ganglioside GD2 overexpressed on neuroblastoma. 3F8 has been shown to have a high specificity and sensitivity in the radioimmunodetection of minimal residual disease (MRD) in patients with NB,10 and a significant impact when used as adjuvant therapy.11 
The immune basis of clinical tumor response to MoAb is at least two fold, direct cytotoxicity and induced immunity. Antibody dependent cell-mediated cytotoxicity (ADCC) and complement-mediated cytotoxicity (CMC) are responsible for the direct killing of tumor cells. On the other hand, through tumor opsonization12 or idiotype network,13 tumor-specific immunity is induced. With this paradigm, how the body eliminates microbial pathogens remains highly relevant in our strategic approach to cancer therapy. Since the first description of innate immunity and acquired immunity model, several components have emerged center stage.14 Antibodies, complement, phagocytes, and “danger” receptors are core elements of innate immunity while antigen-presenting cells, T and B lymphocytes constitute essential players in acquired immunity. Despite the availability of tumor-selective monoclonal antibodies and the ample supply of phagocytes/natural killers, shrinkage of established tumors following antibody treatment alone, and the acquisition of specific immunity, are not common in both preclinical models and cancer patients. The absence of a danger signal and the diminution of complement action by complement resistance proteins on tumor cells may explain the inefficiency of antibody mediated clinical responses.15 LPS and beta-glucan, being cell wall components of bacteria and fungus, respectively, are potent danger signals to the immune systems in all life-forms, from Drosophila to man.16 While LPS is too toxic for human use, β-glucan is a relatively benign structural component extractable from cereals, mushrooms, seaweed and yeasts.17 They are made up of 1,3-β-D-glucopyranosyl residues along which are randomly dispersed single β-D-glucopyranosyl units attached by 1,6-linkages, giving a comb-like structure. The 1,3-β-backbone and the 1,6-linked branches were thought to be important for their immune effects. Lentinan (from Lentinus edodes, Basidiomycete family) with 1,6 branches at mean of 3 main chain units, is licensed Japan for cancer treatment. Schizophyllan (from Schizophyllum commune, Basidiomycete family) and β-glucan from Baker's yeast (Saccharomyces cerevisiae) have also similar structures. From seaweed, Laminarin (1,3 β-D-glucan with 1,6-β side chain branching on every 10 glucose subunit along the polymer backbone) has been extracted. Because of its smaller size and water solubility, it was thought to have potential biologic utility. On the other hand β-glucan from barley, oat or wheat have mixed 1,3-β and 1,4-β-linkage in the backbone, but no 1,6-β branches, and generally higher molecular weights and viscosities. In addition, they have not yet been tested for their in vivo immunomodulatory effects in cancer models.
This invention discloses that oral beta-glucans derived from barley or oats can greatly enhance the anti-tumor activity of anti-tumor monoclonal antibodies in xenograft models. Given the low toxicity of oral β-glucan, their role in cancer therapy deserves careful study.